1. Field of the Invention
The present invention relates to a method of controlling a power supply and a printer adopting the same. More particularly, this invention is directed to a power supply controlling method for controlling the supply and interruption of power of an external power source to and from the power supply which generates power required to drive a printer.
2. Description of the Related Art
Referring to FIG. 1, a conventional printer 10 receives print data from a computer 20 via a communications interface.
The printer 10 includes a printer controller 11 for processing the print data and controlling the entire system, an operation panel 13 having an operation key for outputting an operation signal to the printer controller 11, a printer engine 12 controlled by the printer controller 11 to perform practical printing on a paper sheet and a power supply 14 for receiving power from an external power source 15 to supply power to elements including the printer engine 12.
In the printer 10 in which an ink is employed as a developer, the printer engine 12 includes a driving means for driving a circulating photosensitive belt, a laser scanning unit for irradiating light beams onto the photosensitive belt to form an electrostatic latent image, a developing apparatus for developing the electrostatic latent image, a transferring apparatus for transferring the image developed on the photosensitive belt to a paper sheet, and a resetting apparatus for removing the electrostatic latent image formed on the photosensitive belt and for electrically resetting the photosensitive belt so that a new electrostatic latent image can be formed.
In the printer engine 12, some apparatuses which need to be maintained at a constant temperature, e.g., a heating pressure roller of the transferring apparatus for fixing a toner image to the paper sheet, must receive power continuously to maintain the constant temperature.
However, if the printer is not used for long periods of time (while in a power-on state), the ongoing power supplied to the printer is wasted. Therefore, most printers employ a warm-up mode, which is one of several power supply modes which reduce power consumption when the printer is idle. In the warm-up mode, power which is appropriately lowered below the value required for printing, is supplied to the print engine 12 to maintain required temperatures.
However, the warming-up mode having the lowered power still consumes approximately 10 watts of power. Thus, if the printer in a power-on state is not used for a long time, or if the power supply is not cut off due to carelessness of the user, much power is wasted.
Also, after executing a power supply switch to first supply power to the conventional printer 10, the temperature of a thermal element must be increased, such as the heat pressure roller, up to a predetermined temperature so that a printable state is attained. Thus, a long period of waiting time is required for printing after initially switching the printer on.